Electrolytic apparatus.



I. L. ROBERTS.

ELBGTROLYTIG APPARATUS.

APPLICATION FILED APE. 3, 1905.

Patented Oct. 5, 1909.

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rairnerr herren,

ISAIH l.- EGBERTS, OF NEW' YGRII, N. Y.

ELEC'ROLYTIC AEPARATU.

Sp'eceaton of Letters Patent.

Patented Urt. 5, i909.

Application led April 3, 1905. Serial No. 25,384.

Yori: invented certain new and useful l covements in ElectrolyticApparatus.y of 1 1 wlnc ne foliowmgis specication, relerv had to thedrawings accompanyrzning a part of the seine.

inve tion relates to porons dias :for e. in batteries and electro'-cells.' Hereofore such diaphragme been of various substances and f s, asfor example, of clay molde-d and then baked at a .high temperature; ofcements and various other mineral, vegetable and animal substancesmolded and halted; also of anthracite coal and other carbonaceousmaterials, the particles of same being hell between suitable mechanicalsupports, or cemented together. All theseA devices are more or lessaffected by the acids or alhalies with which they come in contact, whilethe anthracite diaphragme possess the disadvantage of requiring the useof cement or mechanical supports to hold them in forni. Efforts havebeen made to use a porous diaphragm or eonducring carbon, but withoutsuccess, for the reason that, being conducting, the diaphragm will onclosing the electrical circuit through it assume a polarity of its own,side beconfiinggjr positive and the other negative, thus setting up adouble action in the battery or electrolytio l have therefore been ledto devise my present invention, which has for its object the productionof a porous diaphragm which is light and strong and which willbe'aiiected to a minimum degree, it' at all, by the liquid or liquids inwhich it is used; and. also the provision of-a simple and elhcientapparatus in which such a diaphragm be employed;

. ln carryingq out the first part of my invention l 'take a sheet orvessel of wood, wood pulp.7 paper, strawboard, or similar material, ofthe proper size fior the. purpose desired, and char or partiallymirbonize the same, suiiiciently to change the organic niaterialstherein into acoiuilition in which they willV notV attached by theelectrolyte, at

.the Same time without' rendering the `diaphragm suiiciently. conductingto up double electrolytic action. F or example, in making' a diaphragmin the forni or` a cup, l' may taire a bloclrof wood and turn from it acup or vessel of the desired form and size, allowing of course for theusual slirinl age 1n the process of carbonization. The cup is thenplaced in a suitable oven and heated very slowly, keeping` thetemperature 'as nearly as possible uniform throughout all parts of thevessel. The heating should be` carried only to such a degree that thediaphragm will be charred wit-hout becoming conducting to an appreciableextent.. lt' `the vessel is made from wood of goed quality, that is, oferen grain, free from cracks, etc., it will retain its for i veryclosely. Instead of making the vessel from wood, by turning the sainefrom a solid bloclz, it may be formed by molding wood-pulp, or similarmaterial, in a plastic state, or may be built up from sheets of them inany suitable manner. Such a vessel is the-n carbonized in the manner asjust described.

lf the diaphragm to be in the form of a fiat plate or sheet, it shouldbe prevented from warping or twisting in the process of carbonization,and for this purpose I use a pair of pl'ates of iron or other suitablematerial, between which the sheet is clamped during the baking,apertures being provided in the clamping plates to permit escape of thegases of decomposition. The extent to which the diaphragnis are to beheated with- `out rendering them conducting varies, of

course, with the materials used. Within certain limits, however, it isimmaterial at what point t-he carbonization is stopped, since it may becarried considerably beyond the point where the material becomessuiiciently resistant to the attack oi acids or alkalies used ordeveloped in the electrolyte or battery solution, Without the diaphragmbecoming sufficiently conducting to render it useless for, the purposeintended. It is impossible, on account of the wide ditl'crences in thesubstances from which the dia phra gms may be made, to give deinitetemperatures, or degrees of carbonization, to which they may or shouldvbe subjected, but these facts may be readily ascertained foranyparticular kind of material by preliminary trial. iii/'here theelectrolyte is i watery that is, a liquid at ordinary temperatures, incontradistinction to a fused bath, the heat used to carbonize thediaphragm should be no higher than is necessary to decompose the organicmatter to such a degree that itwill not be attacked by thel gasesproduced in the electrolysis or by the substances in the solution.

For example, 'chlorin gas will `soon decompose such organic materials aswood, paperboard, strawboard, wood-pulp, etc., but if these arepartially carbonized, as described,

' the ysubstancesv wliicli. would unite `.with

chlorin are decomposed or'driven o' in the baking, leaving the diaphragmin proper form and of sutlci'ent strength `to be used for the purposeintended.

For molten baths a cup diaphragm will generally be found more suitable,since 1t does not require the use ofsealed Joints 1n contact with thefusedelectrolyte; whereas Hat diaphragms usic-.d toy divide a tank intocompartments requires the joint which its edges make with walls of the'tank to be scaled, as for `exa1nple,jby ,means of asphaltum, paraffin',or similar material. The substances just mentioned melt at comparativelylow temperatures, and hence `:ould not withstand the heat of fusedelectrolytes, which usually are kept at higher temperatures than themelting point of asphaltum, parailin, etc. On the other hand, a hollowdiaphragm, as a cup or other yessel, may be plunged to the desired depthinto the molten electrolyte wh-ile the seal at the top of the cup, incases where a seal is desirable, remains out of contact with the bathand may be kept at a much lower temperature.

Referring now to the drawings for a more complete explanation of myinvention: Figure l is a perspective view, showing a vessel or lcupready for carbonization. Fig. 2 is a plan view, showing a convenientclamping device for use in making flat plates or sheets. Fig. 3 is aside elevation of the clamping apparatus.

Referring now to Fig. l, A indicates a vessel in the form of acylindrical cup, made of turned wood, or molded or otherwise shaped,from any of the materials already mentioned, or their equivalents. Itwill of course be understood that the cylindrical form of the vesselshown is not an essential feature of the invention, since the diaphragmmay be of any desired shape. scribed, the vessel is now partiallycarbonized, making it porous and unattackable by the substances in theelectrolyte'or battery solution, or by the gases evolved therefrom, butleaving` it substantially non-conducting.

In Figs. 2 and 3 I have shown convenient clamping device for retaining aflat plate in shape during its process of carbonization.

The apparatus shown consists of two plates of cast-iron, or othersuitable material, indicated by B, 0. These are fastened toy getheratone sidey 1n a convenient manner,

as for example by means of a knuckle joint I), which will permit sheetsof different thicknesses to be firmly clamped. At the edges -of the,plates are suitable clamping devices, such as bolts E, pivoted to earsout# standingfrom the plates, 'and carrying at izing of` the diaphragm.After the daphragrn-sheet has been locked in the clamp, I

it is placed in the oven and baked, being careful,as before, to raisethe temperature very slowly and evenly so that the diaphragm will not becracked by too rapid heating. As the carbonization progresses thediaphragmwill shrink and become loose in the clamp, but if the heatingis gradual and regular no splitting or cracking of the diaphragm willoccur. The cooling should.v also be gradual, so as to produce no suddenlstrain thereon. When the process is completed, it will se found thatthe sheet of Wood, pulp, strawboard,.or other material, as the case maybe, is transformed into a plate of the necessary porosity, andresembling charcoal in its appearance and consistency. The porosity ofthe diaphragm, in whateverv form the same is made, depends, of course,upon the material used, a diaphragm of charred vstraw-board, pulp-board,etc., being more porous than one from a board or vessel of wood.

From the foregoing it will be seen that my invention provides diaphragmswhich are light, cheap', and strong, and withal sub.- stantiallyunaffected by the electrolytic acids or alkalies, etc. It will of coursebe understood that the method of making the diaphragms may be practicedin a variety of ways, so long as it involves the partial carbonizationof a woody article to render itv unattackable by the substances used orevolved in the electrolyte, without making the diaphragm conducting. Bythe term woody I mean not only wood itself, but also wood-pulp; likewisestrawboard, papier mache, paper, and similar organic materials whichwhen partially carbonized retain theirA form to a substantial degreewithout the necessity of using a binder What I claim is:

l. The method of making porous diaphragins, which consists in forming ofwoody material 'an article of the desired shape, and'then partiallycarboniz'ing the vsame throughout to a non-conducting point,

phragms, which'consists in forming an article of'wood, and thenpartially carbonizin the same throughout to a Anon-conducti.'ig

pbint, asset forth.

